Hi, I have a free range flock of 16 and one of my four month old chicks has loose poop. I first noticed it yesterday morning. Not sure if it is normal. She is eating and drinking normally and has plenty of energy.
If you're certain of the pooper, watch her general behavior. If she is slowing down, acting lethargic, poor appetite, then this dark runny poop may have significance.
Absent that behavior, this poop may just signify a high consumption of insects and things with a high water content.
Yes, that would produce such poop. I see this in my flock when my horse neighbor brings me fresh horse manure for my compost bins. The chickens gorge on the insects in it and I see poop such as the stuff in your photo.